Italian 120 millimetre naval guns were standard main armament on Italian destroyers and were widely used on various other ships and coastal artillery. The 50-calibre guns used a charge of of smokeless powder to push a projectile to a velocity of . Velocity was later reduced to , which gave a maximum range of at 45°  elevation or at 35°  elevation. Variants of similar designs were built by Ansaldo, OTO, Vickers, Schneider, Canet and Armstrong. Older and shorter-barreled guns have different ballistics as noted below.

40-caliber Armstrong 1889 and 1891 These were British QF Mark I and III guns used as coastal artillery and as star shell guns aboard s.

50-calibre M1909 These guns formed the original secondary battery of and s and were later used for coastal artillery. They fired a projectile at .

45-caliber Armstrong 1918 These guns were developed from the older 40-calibre models and installed as coastal artillery and aboard troopships and armed merchant cruisers. They fired a projectile at . Range was at the maximum elevation of 30°.

45-calibre Schneider-Canet-Armstrong 1918 These guns with a maximum elevation of 30° were installed as coastal artillery and aboard auxiliary ships.

45-calibre Schneider-Canet-Armstrong 1918/19 This gun was a twin mounting of the 1918 gun with maximum elevation increased to 32° . These guns were the main armament of s and the sloop .

45-calibre Vickers Terni 1924 These guns were the main armament of s. A charge of of smokeless powder pushed projectiles at to a range of at the maximum elevation of 33°; but dispersion was increased by using a common cradle for the 16.6-ton twin mount.

27-calibre OTO 1924 These were the original deck guns aboard and the s. When replaced by the 45-caliber OTO 1931, these guns were installed as an anti-aircraft battery at Messina where they fired projectiles at a velocity of to a ceiling of .

45-calibre OTO 1926 These guns were the OTO version of the Vickers Terni 1924 guns. s were built with these guns as the main armament, and s were re-armed with these guns.

50-calibre Ansaldo 1926 These horizontal sliding breech block guns in 20-tonne common-cradle twin mountings with maximum elevation of 45° were the main armament of the , , and s.

45-calibre OTO 1931 These 3.2-ton quick-firing guns with a horizontal sliding breech block were mounted aboard Ettore Fieramosca, , Balilla, and submarines. They fired a projectile at . Range was at the maximum elevation of 32°.

50-calibre OTO 1931 These horizontal sliding breech block guns in common-cradle twin mountings with maximum elevation of 33° were the main armament of s.

50-calibre OTO 1933 These horizontal sliding breech block guns in 34-tonne common-cradle twin turrets with maximum elevation of 42° formed the secondary battery of the rebuilt Conte di Cavour-class battleships.

15-calibre OTO 1933 and 1934 These were star shell howitzers installed aboard s and Maestrale, and s. The guns elevated to 50° to fire a shell at to an effective range of .

50-calibre OTO 1936 These horizontal sliding breech block guns in common-cradle twin mountings weighing 22.8 tonnes with maximum elevation of 35° were the main armament of Oriani-class destroyers.

50-calibre Ansaldo 1936 These horizontal sliding breech block guns in common-cradle twin mountings weighing 21.6 tonnes with maximum elevation of 40° were the main armament of some Soldati-class destroyers.

50-caliber Ansaldo 1937 These horizontal sliding breech block guns in common-cradle twin mountings weighing 21.6 tonnes with maximum elevation of 42° were the main armament of other Soldati-class destroyers.

50-caliber Ansaldo 1940 These horizontal sliding breech block guns in 12-tonne single mounts with maximum elevation of 45°  replaced the star shell howitzer of Soldati-class destroyers Bombardiere, Camicia Nera, Carabiniere, Corsaro, Geniere, Lanciere, Legionario, and Mitragliere.

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